1. Field of the Invention
The invention relates to an image-capturing apparatus and method, and more particularly relates to an image-capturing system and method with compression technologies.
2. Description of the Prior Art
Most computer systems use a form of raster image to output image data to a visual output device such as a cathode ray tube (CRT) monitor, liquid crystal display (LCD), or a printer such as a color laser copier. A raster image is represented as a series of scan lines of pixels, wherein each pixel is accessed in a sequential manner, and each scan line is processed. An area to which image data may be output sequentially by the visual output device is referred to as a page. The image data of a page provides its complete visual representation.
Interpreters of page description languages typically process images in one or both of two modes: band mode and frame mode. Both of these however generally require a buffer memory which can hold the entire visual representation of a page, it is desirable to reduce the buffer memory requirements, for example by using some form of compression. In general apparatus of image-capture, such as a scanner, there are two models in a technology of compression. “Loss-less” is one that image data captured by the scanner is decompressed without distortion, while “Lossy” is one that the image data is distorted after decompression. One compression method is shown in U.S. Pat. No. 6,269,190 to Mikkelsen et al. related to processes and apparatus for processing image data. A page of an image is divided into several regions. Each of these regions may be compressed according to a different technique according to the kind of data within the region. Each region can be compressed with a method that works well for the data contained in that region.
Another compression method is shown in U.S. Pat. No. 6,097,845 to Ng et al. It is for discriminating among image characteristics in order to select among a plurality of compression techniques. Multiple compression schemes are applied to a source image concurrently and the results are stored. Image discrimination is performed in parallel with the image compression to generate a recommendation regarding the stored compressed images.